Ergonomic base and chair providing constrained lateral movement there between

ABSTRACT

A base for a chair, the base comprising a chassis ( 11 ), at least one landing ( 20 ) operatively connected to the chassis; a carrier ( 32 ) for reduced friction sliding along the landing transverse to the forward facing direction of the occupant; the carrier being adapted to support a pedestal ( 40 ) upon which the chair is operatively mounted. The base may include a foot rest ( 14 ), brake means ( 49 ) to prevent sliding when the seat is not occupied and wheels between the chassis and floor to permit movement of the seat transverse to the sliding of the carrier. The wheels may be lockable. The landing may comprise an inverted U channel in which rollers slide from which the carrier may suspend underneath the chassis.

The invention relates to chairs and chair bases and more particularly toa chair and chair base for reducing back strain in occupationalsituations where lateral movement from a seated position is anadvantage.

Many occupational situations require lateral or side to side movement ina sitting position. Dealers and croupiers in casinos, postal sorters,office workers and receptionists etc. are often required to slide fromside to side in the course of their work. In a healthy individual, thiskind of repetitive motion may be a source of strain or injury. In aperson with an existing back injury, this kind of motion may precludethem from working effectively, or at all. As the lateral motion isaccomplished largely by the base of the chair (as opposed to the seat)there exists therefore, a need for a chair, or for a chair base adaptedto receive a seat, which allows the user to move laterally, with minimumeffort.

It is desirable that a chair or chair base be provided that alleviatesthe above problems.

According to a first aspect of the invention, there is provided a basefor a seat or chair comprising

a chassis;

a landing provided on the chassis;

a carrier slideable in a “sideways” direction along the landing, thecarrier being adapted to support or capable of supporting, a seat orchair facing or able to face, an “in” direction which is at 90° to said“sideways” direction;

a carrier braking means having a friction material that is moveabletowards and away from the landing, the carrier braking means being suchthat the carrier can only be freely slid along the landing when thebraking means is released;

the braking means being releasable by the weight of an occupied seat orchair that serves to move the friction material away from contact withthe landing and thus release the braking means, which is otherwiseadapted to cause the friction material to remain in contact with thelanding.

The carrier braking means may include a compressible member adapted tobe compressed by the weight of the occupied seat or chair to move thefriction material away from contact with the landing.

The chassis may be provided with means to facilitate it being moved inopposite “in” or “out” directions. Said means may include wheels thatare retractable with respect to the chassis. In particular, said meansmay include lockable wheels.

The landing may be defined by spaced rails.

The carrier may be supported by wheels, which are positioned on saidrails to permit movement of the carrier with respect to said rails.

The invention extends to a base, as described above, in a combinationwherein the carrier supports a seat or chair facing, or able to face, an“in” direction which is at 90° to said “sideways” direction.

According to a second aspect of the invention, there is provided a basefor a seat or chair, the base comprising

a support structure;

a carrier that is arranged on the support structure, a seat or chairbeing mountable on the carrier to be supported above the supportstructure;

a linear displacement mechanism to permit linear displacement of thecarrier relative to the support structure; and

a brake mechanism that is arranged between the carrier and the supportstructure to inhibit linear displacement of the carrier relative to thesupport structure, the brake mechanism being biased into an operativecondition when the seat or chair is not in use and being releasable whena threshold weight bears on the carrier, said threshold weight beingbased on a selected minimum weight of a person envisaged using the seator chair.

A number of wheels may be mounted on the support structure to facilitatemovement of the support structure relative to a substrate. The base mayinclude a retracting mechanism that is operable on the wheels to retractthe wheels. Further, the base may include a locking mechanism that isoperable on the wheels to lock the wheels against rotational movement.

The support structure may include at least two spaced, substantiallyparallel, elongate members, the carrier being supported on the elongatemembers and being displaceable along the elongate members, the elongatemembers being of sufficient length to provide a desired extent ofmovement of the carrier.

The carrier may include at least two engaging formations that areslideably engaged with respective elongate members so that the carrieris slideable with respect to the elongate members. The elongate membersmay be circular cylindrical and the engaging formations may be in theform of collars that are slideably mounted on the respective elongateelements.

The carrier may include at least two wheel arrangements. Each wheelarrangement may include a weight bearing roller that is rotatablyengaged with a respective elongate member so that the carrier can bewheeled back and forth along the elongate members.

Each elongate member may be shaped to define an operatively uppersupport surface on which the respective weight bearing rollers aresupported.

Each wheel arrangement may include a guide roller that is engageablewith a respective elongate member to guide movement of the carrier onthe elongate members.

In a further embodiment, each elongate member may define a suspensiontrack and each wheel arrangement may define a bogey that is positionedon a respective track, the carrier being suspended from the bogeys.

According to a third aspect of the invention, there, is provided a chairthat includes a base as described in the second aspect of the invention.

A base for a seat or chair and a chair in accordance with this inventionmay manifest itself in a variety of forms. It will be convenienthereinafter to describe in detail preferred embodiments of the inventionwith reference to the accompanying drawings. The purpose of thisspecific description is to instruct persons having an interest in thesubject matter of the invention how to carry the invention intopractical effect. It is to be clearly understood however that thespecific nature of this description does not supersede the generality ofthe preceding broad description. In the drawings:

FIG. 1 is a perspective drawing of a chair base adapted to receive achair for lateral movement;

FIG. 2 is a plan view of an alternative chair base;

FIG. 3 is a partly sectioned side elevation of a chair base and part ofa chair for lateral movement omitting the chassis members;

FIG. 4 is a plan view of the device shown in FIG. 3;

FIG. 5 is rear elevation of the chair base shown in FIG. 3, fitted witha cover;

FIG. 6 is a side view of a lockable wheel assembly;

FIG. 7 is a perspective drawing of a chair base adapted to receive achair for lateral movement;

FIG. 8 is a perspective drawing of the inverted chair base of FIG. 7;

FIG. 9 is a perspective drawing of a bogey on a channel type landing;

FIG. 10 is a cut away perspective drawing of an inverted bogey on achannel-type landing; and

FIG. 11 is a perspective drawing of a retractable wheel assembly.

The subject matter of this disclosure pertains to an ergonomic chair.The chair includes a base, a pedestal and a seat. The base includes afriction reducing mechanism. The pedestal extends between the base andthe seat. Any number of types of seat may be suitable for use with thedisclosed base. The invention is therefore not limited to any particularseat.

As shown in FIG. 1, a base 10 for a chair includes two side chassismembers 11. Each chassis member 11 supports, along a portion of itsmid-section, the ends 13 of two parallel rods 12. The rods 12 may be upto several meters long if required. The rods 12 act to support asuitable form of bearing for linear motion along them. Alternatively,rails may be used in place of rods. Together with other known means forsupporting a weight for linear motion the terms “rail” and “rod” areused as examples of landings.

Each chassis member also supports one end of a pivoting, adjustablefootrest 14. The position of the footrest 14 is governed by a ratchetand pawl or detent mechanism 15 whereby the elevation of the footrest 14may be maintained against the weight of the user, until it is adjusted.

The parallel rods 12 support a sliding carrier 16. The carrier 16includes bearings 17 which slide on the rods 12 so that the carrier cantraverse, laterally, a space between the chassis members 11 as shown bythe arrows. The carrier 16 extends between the bearings 17. A chairsupport 18 is fixed to the carrier 16 and is shaped to receive the postor pedestal of a chair. Any suitable chair on a post or pedestal can inthis way be incorporated onto the base. Where circumferential linearbearings 17 are used with ground rods 12, lateral motion is accomplishedwith little frictional resistance. In this example, four bearings 17 areprovided.

As shown in the alternative construction of FIG. 2, the carrier 16 maybe triangular and provided with three bearings 17, one on one rod 12 andtwo bearings 17 on the other rod 12. This reduces friction, weight andcost.

Another embodiment is depicted in FIGS. 3-6. As shown in those Figures,the rods 12 have been replaced with rails 20. In this example,rectangular tubes are used as rails 20. This allows friction reducingbearings to reside within rollers or wheels 21 rather than bear directlyon the rails 20. Polymeric rollers or wheels 21 (e.g. nylon or urethane)which are supplied with bearings may be supported by a stamped andpressed sheet metal carrier 32. Roller blade and skateboard wheels maybe suitable with little or no modification.

To prevent the rollers 21 from disengaging the rails 20, stabilizingrollers 22 are supported by the carrier 32. The stabilizing rollers 22are maintained so that they engage the lower outside edge 23 of therails 20. Openings 24 in the carrier 32 through which the rollers 21, 22extend are punched directly into the sheet metal forming the carrier 32.The metal displaced from the forming of the openings 24 is used to formthe ears 25 which support the axles or fasteners 26 which pass throughthe various rollers 21, 22.

In this example, a triangular carrier is used with three pairs ofrollers 21, 22. The front and rear edges 27, 28 of the carrier 32 areprovided with a radius so that the weight bearing rollers 21 and thestabilizing rollers 22 can be supported by the same stamped and pressedpiece of sheet metal. This stamping 33 may be joined to a reinforcement,such as another stamped piece of sheet metal 34. Preferably, this isaffixed to one end 46 of a rigid collar 35 formed in the centre of thecarrier 32. The other extremity 36 of the reinforcement 34 is attachedto the portion of the carrier 32 that supports the rollers 21, 22.

The opening of the collar 35 receives a taller collar 40. The collar 40serves several purposes. Its main function is to receive and support thepost or pedestal 44 of the seat 42 (not shown in FIG. 3). It has aninternal bore 43, which may be tapered to receive a tapered pedestal 44.An end 45 of the collar 40 extends beyond the lower edge 46 of thecollar 35. This end 45 attaches to a brake 47. The brake 47 comprises arigid bar 48 that extends between the rails 20 (or rods 12). Each end ofthe bar 48 has brake pads 49 which engage the rails tightly when thereis insufficient weight on the seat 42. When a predetermined weight isreached (when someone sits down) a compression spring 50 is overcome.The taller collar slides in the collar 35 against the resistance of thespring 50. This moves the brake 47 away from the rails 20 and allows thecarrier 32 to move freely with respect to the rails 20. An alignment pin51 extends from the brake bar 48 through a clearance hole 52 formed inthe carrier 32. This keeps the brake 47 in alignment with the rails 20.

More direct means may be used to attach the pedestal 44 to the uppersurface or part of the carrier 32.

To allow the entire base to slide in and out, the chassis members 11 aremounted on wheels or castors. As shown in FIG. 1, wheels or castors 60may be mounted on or under the chassis members 11.

FIG. 6 illustrates a spring biased detent mechanism 61 for locking awheel 60. The mechanism 61 includes a handle 62 which lifts a spindle 63out of engagement with a wheel 60. The wheel 60 includes radial openings59. In the “down” or “free” position 64, the spindle 63 is free of thewheel openings 59.

As shown in FIG. 4, the parallel rails 20 are supported at each end bychassis members 11. Each chassis member 11 may be equipped with wheels60 so that the entire base may be rolled in and out.

As shown in FIG. 5, the base can include a rigid cover 70 with footrestfeatures formed directly on it.

Another embodiment is depicted in FIGS. 7-11. As shown in FIG. 7, thebase 100 has chassis members 101 formed from rectangular steel tubes andtwo landings 102 formed from steel channel. Each chassis member 101supports one end of an adjustable footrest 103. A retractable wheelassembly 104 is positioned on each chassis member, forward of thefootrest 103. A carrier 105 rides on the landings 102, suspended frombogeys 111 (see FIGS. 8-10). The carrier 105 can be of cast metal.

As shown in FIGS. 8, 9 and 10, each landing 102 is in the form of aninverted “U” shaped channel. Sides or edges 110 of the channel are bentinwards to form parallel grooves. The grooves serve as a track forwheeled bogeys 111. In this example, each of the three legs 112 of thecarrier 105 is suspended from a four wheel bogey 111. A single groovelanding in the form of a “J” could be employed and would be lessexpensive but less robust, more vulnerable to dust and dirt build up andless stable.

Each bogey 111 has two pairs of wheels 113 which are interconnected by acentral tie 117.

A suspended threaded shaft 114 is affixed to the middle of the tie 117and extends out of the channel 102. The carrier leg 112 is slidablyaffixed to the threaded shaft 114 by a nut 115. A yoke 116 distributesthe load imposed by the tightened nut 115 bearing on the sleeve 124, andbears on the ends of the tie 117. In the case of the single front leg112 in this example (as shown in FIG. 7), a single brake mechanism 120(FIG. 10) is provided between the nut 115 and the yoke 116. The brakemechanism 120 includes an O-ring 122. The nut 115 bears directly on afirst flange 123 formed on the end of a sleeve 124 which fits around theshaft 114. A sliding sleeve 125 has a second flange 126. Under load, thefront leg 112 acts on the second flange 126 to compress the O-ring 122until the sliding sleeve 125 bottoms out against a shoulder 127 definedby the sleeve 124. When a person gets off the seat, the O-ring expandsto its original shape and urges the carrier mounted circumferentialurethane pad 121 into contact with the channel 102. This acts as asafety brake when there is no load and inhibits the carrier from slidingon the landings.

Each end of the tie 117 is affixed to a pair of wheels 113. In oneembodiment, the wheels 113 have a metal core and a polymeric contactsurface. Each wheel 113 is mounted, via bearings, on a cross shaft 128.The small clearance between the top of the wheels 113 and the interiortop 129 of the channel prevents excessive motion of the bogey.

FIG. 11 illustrates a retractable wheel assembly 104 mounted within aforward portion of a chassis member 101. The assembly 104 utilises apair of vertical slots 151 to trap the shaft 153 of a retractable wheel152. The wheel is normally biased into a retracted position (as shown)and may be deployed with a foot pedal 149. The foot pedal 149 pivotsabout a shaft 154. A cam surface 155 urges the wheel down and intocontact with the ground and maintains it there when the foot pedal 149is depressed. This allows the entire base 100 to be wheeled forward andback (ie in and out) on its four wheels 152, 160 (see FIG. 8). When thewheels 152 are retracted, the base 100 rests on its rear wheels 160 andfront pads 161.

Further, it should be understood that the various embodiments of theinvention disclose different components and alternatives which areconsidered compatible with one another for the purposes of chairconstruction.

The present invention has been described with reference to particulardetails of manufacturing. It should be appreciated that these areprovided by way of example and not as limitations to the scope or spiritof the invention.

It will of course be realised that the above has been given only by wayof illustrative example of the invention and that all such modificationsand variations thereto as would be apparent to persons skilled in theart are deemed to fall within the broad scope and ambit of the inventionas is herein set forth.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.

What is claimed is:
 1. A base for a seat or chair comprising: a chassis;a landing provided on the chassis; a carrier slidable in a firstdirection along the landing, the carrier being adapted to support, orcapable of supporting, a seat or chair facing, or able to face, in asecond direction which is at about 90 degrees to said first direction;and a carrier braking means having a friction material that is movabletowards and away from the landing, the braking means being such that thecarrier can only be freely slid along the landing when the braking meansis released, the braking means being releasable by the weight of anoccupied seat or chair that serves to move the friction material awayfrom contact with the landing and thus release the braking means, whichis otherwise adapted to cause the friction material to remain in contactwith the landing.
 2. A base according to claim 1, wherein the carrierbraking means includes a compressible member adapted to be compressed bythe weight of the occupied seat or chair to move the friction materialaway from contact with the landing.
 3. A base according to claim 2,wherein the chassis is provided with means to facilitate the chassisbeing moved in the second direction and in a third directionsubstantially opposite the second direction.
 4. A base according toclaim 3, wherein said means includes wheels that are retractable withrespect to the chassis.
 5. A base according to claim 3, wherein saidmeans include lockable wheels.
 6. A base according to claim 1 whereinthe landing is defined by spaced rails.
 7. A base according to claim 6wherein the carrier is supported by wheels, which are positioned on saidrails to permit movement of the carrier with respect to said rails.
 8. Abase according to claim 1 in a combination, wherein said carriersupports a seat or chair facing, or able to face, the second direction.9. A base for a seat or chair, the base comprising: a support structure;a carrier that is arranged on the support structure, a seat or chairbeing mountable on the carrier to be supported above the supportstructure; a linear displacement mechanism to permit linear displacementof the carrier relative to the support structure; a brake mechanism thatis arranged between the carrier and the support structure to inhibitlinear displacement of the carrier relative to the support structure;and biasing means for biasing the brake mechanism into an operativecondition when the seat or chair is not in use, the biasing means beingovercome when a threshold weight bears on the carrier, said thresholdweight being based on a selected minimum weight of a person envisagedusing the seat or chair.
 10. A base according to claim 9, in which anumber of wheels are mounted on the support structure to facilitatemovement of the support structure relative to a substrate.
 11. A baseaccording to claim 10, which includes a retracting mechanism that isoperable on the wheels to retract the wheels.
 12. A base according toclaim 10, which includes a locking mechanism that is operable on thewheels to lock the wheels against rotational movement.
 13. A baseaccording to claim 9, in which the support structure includes at leasttwo spaced, substantially parallel, elongate members, the carrier beingsupported on the elongate members and being displaceable along theelongate members, the elongate members being of sufficient length toprovide a desired extent of movement of the carrier.
 14. A baseaccording to claim 13, in which the carrier includes at least twoengaging formations that are slidably engaged with respective elongatemembers so that the carrier is slidable with respect to the elongatemembers.
 15. A base according to claim 13, in which the elongate membersare circular cylindrical and the engaging formations are in the form ofcollars that are slidably mounted on the respective elongate members.16. A base according to claim 13, in which the carrier includes at leasttwo wheel arrangements, each wheel arrangement including a weightbearing roller that is rotatably engaged with a respective elongatemember so that the carrier can be wheeled back and forth along theelongate members.
 17. A base according to claim 16, in which eachelongate member is shaped to define an operatively upper support surfaceon which the respective weight bearing rollers are supported.
 18. A baseaccording to claim 17, in which each wheel arrangement includes a guideroller that is engageable with a respective elongate member to guidemovement of the carrier on the elongate members.
 19. A base according toclaim 16, in which each elongate member defines a suspension track andeach wheel arrangement defines a bogey that is positioned on arespective track, the carrier being suspended from the bogeys.
 20. Achair in combination with said base as claimed in claim
 9. 21. A baseaccording to claim 2, wherein the landing is defined by spaced rails.22. A base according to claim 3, wherein the landing is defined byspaced rails.
 23. A base according to claim 21, wherein the carrier issupported by wheels, which are positioned on said rails to permitmovement of the carrier with respect to said rails.
 24. A base accordingto claim 22, wherein the carrier is supported by wheels, which arepositioned on said rails to permit movement of the carrier with respectto said rails.
 25. A base according to claim 3 in a combination, whereinsaid carrier supports a seat or chair facing, or able to face, an “in”direction which at 90 degrees to said “sideways” direction.
 26. A baseaccording to claim 7 in a combination, wherein said carrier supports aseat or chair facing, or able to face, an “in” direction which at 90degrees to said “sideways” direction.
 27. A base according to claim 11,which includes a locking mechanism that is operable on the wheels tolock the wheels against rotational movement.
 28. A base according toclaim 10, in which the support structure includes at least two spaced,substantially parallel, elongate members, the carrier being supported onthe elongate members and being displaceable along the elongate members,the elongate members being of sufficient length to provide a desiredextent of movement of the carrier.
 29. A base according to claim 11, inwhich the support structure includes at least two spaced, substantiallyparallel, elongate members, the carrier being supported on the elongatemembers and being displaceable along the elongate members, the elongatemembers being of sufficient length to provide a desired extent ofmovement of the carrier.
 30. A base according to claim 12, in which thesupport structure includes at least two spaced, substantially parallel,elongate members, the carrier being supported on the elongate membersand being displaceable along the elongate members, the elongate membersbeing of sufficient length to provide a desired extent of movement ofthe carrier.
 31. A base according to claim 14, in which the elongatemembers are circular cylindrical and the engaging formations are in theform of collars that are slidably mounted on the respective elongateelements.
 32. A chair in combination with said base as claimed in claim13.